UV Sweeper Instructions

 

3DReefing UV Sweeper Instructions

Updated June 2026 -  PLEASE READ BELOW FOR BEST SUCCESS

 

Pre-Treatment Setup

Before beginning UV Sweeper treatments, prepare your system to support the microbiome shift:

  1. Reduce mechanical filtration – Don't over-filter. Remove carbon media and any GFO. Add a Poly-Filter (or similar pad rated to remove heavy metals) to help pull excess iron out of the water column.
  2. Adjust lighting toward white – Lower intensity slightly and shift the spectrum balance to at least 50% white / 50% blue. This is light-model dependent — some fixtures may need an even higher white ratio to achieve the shift. A whiter spectrum helps encourage beneficial algae films to grow and compete with dinos for space on the sandbed surface.
  3. Pause extra dosing – Stop dosing amino acids, coral foods, and other supplements. Your typical 2-part (alkalinity/calcium) for stability is fine to continue.
  4. DO NOT do any water changes or disturb the sandbed during or after treatment.  Syphoning the sand can severely disrupt the microbiome in your sand and set you back.  

Step 1 — Daily UV Treatment

  • Wear the included Reef Glasses to protect your eyes.
  • Sweep the UV light slowly across the sandbed for 10–15 seconds per area during peak lighting hours, holding it as close to the sand as possible without disturbing it.
  • Move methodically to cover the sandbed.  It is ok if you can not get small areas.  Get as much as you can.  Small areas should clear on their own in time.  

Step 2 — Bacteria Dosing (Recommended - Tropic Marin Nitribiotic)

You don't need to dose after every treatment. Dose at these key points, following label dosage:

  • Immediately after your first treatment
  • Again once the sandbed looks mostly clean (typically around day 3–4)
  • (Optional)  Dose live phyto after EACH treatment.  Typically not necessary but can help.  Make sure it is a good live phyto source and does not smell.  

Step 3 — Post-Dose Flow & Equipment Settings

After dosing bacteria:

  • Turn off all flow (wavemakers/return pump) for 30 minutes.  Let the bacteria settle.
  • Turn off your protein skimmer for at least 4 hours or overnight
  • Keep any in-line UV sterilizer off for the entire duration dinos are present — not just on treatment days. Running it continuously removes the beneficial bacteria you're trying to establish.

Step 4 — Stick With It

  • Continue daily treatments. Results vary tank to tank — some clear up in about a week, others can take up to 30 days.
  • Don't quit prematurely — stopping early resets the process back to square one.
  • If still seeing spots after 10–14 days, slow treatments down to 2–3 times per week until the microbiome has fully shifted.  You can be more lax on treatment and in some cases the rest periods can help.
  • Confirm complete eradication with a microscope before stopping treatment entirely.

A Note on Silicate Dosing

If you've been dosing silicates, there's a high chance you'll see a rapid increase in diatoms (brown dust-like film) shortly after starting treatment — diatoms outgrow dinos in speed and will quickly take advantage of the shift.

This is a good sign, not a setback. The UV Sweeper doesn't kill dinos outright — it sterilizes them so they can't reproduce, while the bacteria and microbiome shift outcompete them over time. As that shift happens, diatoms can temporarily surge into the space dinos are vacating.

Important: Check the sandbed under a microscope to confirm what you're seeing. Many people mistake a diatom surge for "dinos coming back" and assume the UV Sweeper isn't working — when in reality, you're progressing away from dinos and toward diatoms, which will subside once silicate levels deplete (assuming you stop or reduce silicate dosing).

Maintain Stable Nutrients

Keep PO4 at 0.04–0.08 ppm and NO3 at 5–10 ppm to support stability and help prevent recurrence.

Two Common Nutrient Scenarios That Contribute to Dinos

1. Nutrients are bottoming out (near 0 ppm)

Tanks that easily run nitrate and phosphate to 0 can starve the bacteria colonies that keep dinos in check. This can seem "healthy" when stable, but left unchecked it weakens the microbiome over time.

  • Action: Simply dose nitrate and phosphate back up into the target range above. This alone is usually sufficient.

2. Nutrients are elevated and dinos appeared anyway

If PO4 and/or NO3 were already running high when dinos showed up, this usually points to a carbon deficiency — your nitrate, phosphate, and carbon are out of balance. A common sign of this is struggling to lower nitrates even with normal export methods.

  • Action: Begin dosing a carbon-dosing product such as Tropic Marin NP-Bacto Balance to help bring carbon back into balance with your nutrient levels.  We recommend only doing 1/2 the recommended dose during UV Sweep treatments.

Other Factors That Can Cause Dinos to Return

  • Overdosing amino acids — Reduce or pause amino acid dosing and monitor for improvement over several days.
  • Elevated iron / trace imbalances — Run an ICP test to identify imbalances, then adjust trace dosing based on results; avoid blind dosing of trace elements (see Pre-Treatment Setup).
  • Lighting too blue — Gradually increase white channel intensity (see Pre-Treatment Setup), then monitor the sandbed over 1–2 weeks for improvement.
  • Worn-out RODI resin — Replace your color-changing resin once it shows more than 75% exhaustion, even if TDS readings still show 0.

 

Troubleshooting

Still seeing dinos after 14 days?

  • Slow treatments to 2–3x/week (Step 4)
  • Confirm under microscope — rule out a diatom surge (see Silicate Dosing note)
  • Recheck nutrient levels against the two scenarios above
  • Test trace elements via ICP
  • Review amino acid/iron dosing.  High iron and amino acids will fuel dinos.
  • Check your RODI system

Remember: treatment can take up to 30 days. Patience is key — don't stop early.

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